Why this page exists
Two things dominate every veneer purchase conversation: price and grade. Yet the reject panel coming off the press is usually caused by neither — it is caused by moisture, and moisture is the one parameter almost nobody asks about when comparing offers.
It is measurable and it can be written into a contract. There is no good reason not to ask.
The physical mechanism
A hot press runs at 110–140 °C. At that temperature the water inside the veneer boils. The glue has not cured yet, the steam has nowhere to go, and it builds pressure between the plies.
| Moisture content | What happens in the press |
|---|---|
| Below 3% | Veneer turns brittle and cracks during handling and lay-up. Glue is absorbed into the pores |
| 5–8% | The working band. Steam pressure stays below the rate at which the glue cures |
| 8–10% | The common shipping band in this trade. It works, but there is no margin left |
| 10–12% | Blister risk climbs fast; the press cycle has to be extended |
| Above 12% | Blisters, internal voids, delamination; the panel can burst as the press opens |
The critical point: none of these defects can be corrected after pressing. A blistered panel cannot be sanded out or repaired — it is scrap. Moisture content directly sets the output quality of your line, and the decision is irreversible.
What happens on the voyage
Inside a container it is hot by day and cold by night. The swing produces condensation, and water drips onto the cargo from the roof and the walls. Three things work against it:
- Moisture-barrier film. It seals the outer surface of the bundle; a bundle that arrives with torn film is the riskiest one in the batch.
- Dunnage battens. They lift the bundle off the floor. Direct contact with condensation pooled on the container floor is the single most common cause of damage.
- Strapping. A tight bundle absorbs moisture through its edges more slowly.
Measurement: two methods, one of them binding
| Method | How | Accuracy | When it is used |
|---|---|---|---|
| Moisture meter (on the floor) | Pin-type or pinless instrument, in contact with the bundle | About ±1% | Quick check at unloading |
| Oven-drying (laboratory) | Sample dried at 103 °C to constant mass, moisture calculated from the weight loss | Reference method | The result that settles a dispute |
Write into the contract which method is the reference one. The gap between a shop-floor reading and a laboratory reading is the source of most of the arguments that surface later.
The measuring point should be specified as well: the outer layer of a bundle and its inner layers give different figures. Standard practice is the average of several samples taken at different depths in the bundle.
What we do on our side
- Veneer coming off the drying line is brought to the 5–8% band.
- Moisture is measured before dispatch and the figure is written into the shipping documents.
- Packing: strapping, dunnage battens, moisture-barrier film.
- You are expected to measure again on arrival — the comparison against the documented figure is what any claim rests on.
Storage rules
| Rule | Reason |
|---|---|
| Indoors and dry | Wood draws moisture from the air; a few days in the open is enough to do damage |
| Level floor, dunnage battens | A bundle in contact with the floor takes up moisture from below and warps |
| Film intact until the moment of use | An opened bundle is exposed to the humidity of the room |
| Consume an opened bundle quickly | A part-used bundle puts its own remainder at risk |
| Monitor warehouse humidity | Above 70% for a few weeks will push the veneer out of the band |
Grade is a separate subject from moisture and the two should not be confused — we set that out in detail on the grades page. Moisture content is the technical condition of the material; grade is a classification by appearance.